Insulating composition.



UNITED STATES PATENT OFFICE.

LEO H. BAEKELAND, OF YONKEBS, NEW YORK, ASSIGNOR TO GENERAL BAKELITECOMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

INSULATING COMPOSITION.

No Drawing.

To all whom it may concern:

Be it known that I, LEO H. BAEKELAND, a citizen of the United States,residing at Yonkers, in the county of Westchester and State of New York,have invented certain new and useful Improvements in InsulatingCompositions, of which the following is a specification.

This invention relates to more or less fluid or mobile compositionscontaining phenolic condensation products, particularly such as aretransformable by simple heating to the infusible state, in which statethey may however retain under some conditions a marked degree ofelasticity, particularly at higher temperatures.

It is now well understood in the art that there exist two well-definedgroups of phenolic condensation products, viz., those which areinitially soluble and fusible but which are transformed by simpleheating to infusible bodies, passing in -the course of suchtransformation through an intermediate state in which they are plasticbut infusible, and gelatinized by certain organic liquids but insolubletherein; and those which are permanently fusible and soluble in varioussolvents, particularly in the presence of free phenols. It is also knownthat the products of the second group, which hay e been variouslydesignated as saliretins or saliretin-resins, novolak, shellac substitutes, phenol resins, etc., and which in their properties more closelyapproximate the natural resins, may be transformed by the action offormaldehyde, or other bodies containing a mobile methylene group, intothe products of the first group. (See U. S Patents 1,038,475 to L.'H.Baekeland, 1,020,593 to J. W. Aylsworth, Belgian Patent 204,811 toKnoll.)

My invention relates particularly to the preparation ofsolutions ofinitial condensation products of the first group, the object of theinvention being to prepare solutions which neither contain, in anymaterial proportion, nor yield by reaction, bodies such as water,ammonia, methyl or ethyl alcohol, acetone, water soluble bodies, orsubstances which attract or retain ammonia or water, acid-reactingsubstances, or the like, or in general any substance which would lessenthe value of the solution, or of the product obtained by hardening thesame, for electrical insulating purposes, particu- SpeciflcationotLetters latent. Patented Feb, 20, 1917.

Application filed October 17, 1913. Serial No. 795,779.

larly where high-frequency alternating currents are involved. In thepreferred embodlment of the invention, I utilize in the preparation ofsuch solutions or compositions a novel phenolic condensation prodnot,which prduct and the method of preparing the same, are claimed in acopending application Serial No. 7 7 6,847, filed July 1, 1913, byBaekeland and Gotthelf.

' ()ne composition in accordance with the present invention may beprepared as follows I incorporate with a suitable solvent preferablyhaving the characteristics hereinafter pointed out, suitable proportionsof a fusible phenolic resin (a fusible phenolic condensation product ofthe second group above referred to) and oil anhydro-formaldehyde-anilin.These reacting. components may be added to the solvent either separatelyor mixed together, or they may be melted or sintered together beforebeing introduced into the solvent. In any case, the resulting mixture isheated to a degree sufiicient to obtain a good solution. In ordinarypractice, the proportion of anhydroformaldehyde-amlin to 100 parts ofthe fusible phenolic resin may vary from 20 to 200 parts. The proportionof these combined ingredients to the solvent may vary within wide limitsup to complete saturation according to the use to which the solution isto be applied.

Anhydro formaldehyde anilin possesses mobile methylene groups, and ishence capable of converting the fusible phenol resins of the secondgroup into the products of the first group, which latter upon sufficientheating are transformed into infusible bodies. The particular advantagepossessed by anhydro-formaldehyde-anilin in this reaction resides in thefact that in contradistinction to all such methylene-containing bodiesas formaldehyde. its polymers and hydrates, the methylene amins,including hexamethylenetetramin, methylene combinations with halogens,alcohol groups, acid radicals, etc., it liberates no gaseous or readilyvolatile by-product in the reaction involved in the transformation ofthe fusible resin of the second group to the infusible product of thefirst group. This fact is particularly advantageous in the case ofproducts intended for the insulation of high frequency alternatingcurrents, where even the smallest traces of water, annnonia, substanceswhich retain water 0' ammonia, or are soluble in water, acid-reactingsubstances, etc.. are highly prejudicial. it is hence highly desirableto provide a solvent which will not detract from the value of theproduct as ali insulator. Forthis purpose therefore the choice of aproper solvent is restricted to bodies-possessing the followingcharacteristics. vi7..:

(l) The capacity of dissolving the initial condensation product withoutthe addition or presence of free phenol or cresol, methyl or ethylalcohol. acetone, esters, nitrobenzol, etc., or of other compounds oflower insulating value than the. solvent itself;

(2) Lack of atlinity for water as evi denccd by substantialimmiscibility therewith;

(3) lligh insulating value, for high tension alternating currents, andfreedom from any too pronounced tendency to become heated under theaction of such currents.

A satisfactory solvent having these characteristics is so-called neutraloil, which is understood to be a high-boiling-point dising proportionscertain high-boiling cyclic hydrocarbons. ()ther appropriate solventsfor electrical purposes are for instance, mono chlor naphthalene,tetrachlorethan (boiling point about 147 (1), chloroform,dichlorethylene (boiling point about 55 Q), ethylenechlorid (Dutchliquid) (boiling point about 84 0.), said solvents being used alone, ormixed, or in conjunction with varying proportions of benzol or itshomologs or other suitable hydrocarbons. For many purposes, as morefully explained below, preference is given to those solvents which havea boiling-point exceeding that of water.

.For the preparation of compositions intended for electri ail insulationit is well to observe the precaution of freeing the fusible phenolicresin from any considerable excess of phenol or cresol by washing withwater, steaming, or otherwise, and then rendering it quite anhydrous bysufficient heating.

The proportion of anhydro-formaldehyde-anilin used exerts a profoundinfluence. upon the character of the condensation product, and thisproportion may therefore be Widely varied according to the nature of theproduct desired. Condensationproducts containing up to 20 parts byweight of anhydro-formaldehyde-anilin to 100 parts of the fusible phenolresin are in general permanently fusible. The higher proportions ofanhydro-formaldehyde-anilin, up to 200 parts by weight for 100 parts ofthe fusible phenolic resin, yield products which ultimately becomeinfusible under continued heating. The hardness of these infusiblcproducts tends to increase up to about 110 to 130 parts ofanhydro-formaldehyde-anilin to 100 parts of the fusible phenolic resin,while products prepared with still higher proportions ofanhydro-forimildelriule-anilin, show increased plasticity at highertemperatures. Y

The resistance of the infusible products to th action of such chemicalsas alcohol, acetone and dilute caustic soda, increases with theproportion of anhydro-formaldehydi-anilin used. For example, productscontaining from 150 to 200 parts of anhydroformaldehyde-anilin to 100parts of fusible phenolic resin, were not apparently acted upon by 10%caustic soda solutions, or by methyl alcohol, after eleven days at roomtemperatures, and were only slightly softened by acetone.

It is to be understood that modifications of my method which involve theformation in the solvent of the anhydro-formaldehydeanilin, or of thefusible phenolic resin, or both, from their components, are within thescope of my invention. Such methods I now regard as less desirable thanthe direct method above described, according to which the pre-formedfusible phenolic resin and anhydro-formaldehyde-amlin are incorporatedwith the solvent, separately or after being sintered or melted togetheror combined by heat.

' My invention is not restricted to the use of the solvents abovementioned as particularly desirable for purposes of electricalinsulation, for I may employ various solvents or mixtures of solventsaccording to the use for which the composition is designed. Among suchuses are The impregnation, filling or coating of coils, for electricalpurposes, and the insulation of electrical conductors;

The impregnation of Wood, paper, woodpulp, cement, porous stone andother porous materials;

The coating of paper and the preparation of composite cardboard;

The preparation of putties, cements, and analogous compositions;

' The preparation of protective; enamels, coatings, varnishes, paints,lacquers and the like;

The manufacture of molding mixtures and molded articles.

For the impregnation of coils, the manufacture of patties and cements,and other uses in which it is desired that little or no evaporationshould occur, it is desirable to select a solvent of which theboiling-point is sufficiently high to permit the reaction whereby theproduct is transformed to its infusible state, to occur Without thesolvent being expelled. Typical solvents of this class are neutral oiland mono-chlor-naphthalene. Heat should be applied to obtain completesolution. About equal parts by weight of condensation product and one ofthe above solvents, give a composition of about the required consistencyfor most purposes, although these proportions may be alteredconsiderably to meet the particular requirements. Greater or lesseramounts of any of the more readily volatile auxiliary solvents may beadded, the high-boiling solvent constituting, however, the main part ofthe solvent. Solutions containing about 50% by weightof neutral oil ormono-chlornaphthalene will gelatinize to an elastic, infusible mass ifheated for about 10 hours at about 110 to 115 C; further heating atthese or somewhat higher temperatures, renders the mass still firmer andharder.

When varnishes, paints and lacquers are to be prepared. the solventshould possess suflicient volatility to permit ready drying;

and when the varnish is to be applied for electrical insulation, thesolvent should possess the characteristics above set forth. Typicalsolvents for such uses are ethylenechlorid (boiling point about 84 C.),dichlorethylene (boiling point about 55 C.), and chloroform, used aloneor mixed, or suitably diluted with benzol.

' If symmetrical dichlorethane (Dutch liquid, chlorid of ethylene) beused as a solvent, it can be diluted with as much as three or four timesits own volume of benzol. Chloroform can stand an addition of about anequal volume of benzol, dichlorethylene, about two volumes, andtetrachlorethane about two to three volumes. Toluene can be used as adiluent only in smaller proportions than benzol.

Satisfactory solutions, applicable for use as "arnishes or lacquers, orwhen mixed with suitable pigments as vehicles for paints, may beprepared by compounding, with aid of heat if necessary, approximatelyequal amounts of solvent and solute; for example, if chlorid of ethylene(symmetrical dichlorethane or Dutch liquid) and the above condensationproduct, pre pared with anhydro-formaldehyde-anilin, while it is yet inits soluble condition, be compounded in about equal proportions byweight, the resulting solution can be diluted as above indicated, as maybe required for particular uses, or more concentrated or thickenedsolutions may be prepared if required.

My invention is not restricted to the use, in conjunction with a solventof high insulating value, of the above-described condensation product ofphenolic bodies and anhydro-formaldehyde-anilin, inasmuch as it is, sofar as I am aware, broadly new to provide a solution in a solvent ofsuch high insulating value as is herein contemplated,

of any initial phenolic condensation product which is capable oftransformation by simple heating into an infusible body. I am aware thatit has been alleged that such condensation products may be dissolved inbenzol, toluol, or mono-chlor-naphthalene, but I have found that thissolution is dependent upon the presence of considerable proportions offree phenols, or nitrobenzol, or acetone or other ketones, alcohol,esters, or similar auxiliary solvents, which reatly reduce theavailability of the resuIting solution for purposes of electricalinsulation. I

In the preparation of industrial products and compositions consisting ofor contain ing the compositions above described it is to be understoodthat I may incorporate such substances, as for example those of afibrous or cellular nature, or powdered fillers or substances formingsolid solutions, as are desirable for particular purposes; heat andpressure to any required degree may be employed for hardening or moldingoperations; and in general I may apply such manipulations and devicesand provide such additions as are now used in this art.

\Vhere reference is made to a solvent of the hydrocarbon type it isintended thereby to include as equivalents in the composition, chlorinsubstitution products of the class mentioned herein as suitablesolvents, as well as neutral oil and equivalent hydrocarbons orhydrocarbon mixtures.

I do not claim'specifically in this application the aforesaid reactionproduct in conjunction With a chlorinated-hydrocarbon solvent, suchsubject-matter being claimed in my divisional application, Serial No.4554, filed January 26, 1915.

The expression product resulting from the reaction of phenols andanhydro-formaldehyde-anilin as used herein, is intended to includeproducts formed by the direct reaction of phenolic bodies or of fusiblephenolic resins with pre-formed or dry anhydro-formaldehyde-anilin, andalso similar products produced by the reaction of phenolic bodies or offusible phenolic resins with anilin and formaldehyde, or with substancesequivalent to these in the reaction.

The expression an initial phenolic condensation product capable oftransformation by simple heating into an infusible body is used herein'to designate those phenolic condensation products which, as

above described, are directly transformed by heat into infusible bodieswithout addition of formaldehyde or other body containing a mobilemethylene group.

I claim 1. An electrical insulating composition comprising an initialphenolic condensation product capable of transformation by simpleheating into an infusible body, and a solvent therefor, said solventbeing of the hydro-carbon type, and characterized by its high insulatingvalue, its immiscibility with water, and its capability of dissolvingthe said initial condensation product after the same has beensubstantially freed from uncombined phenols.

2. An electrical insulating composition comprising an initial phenoliccondensation product capable of transformation by simple heating into aninfusible body, and a solvent therefor, said solvent being of thehydro-carbon type, and characterized by its. high insulating value, itsimmiscibility with water, and its capability of dissolving the saidinitial condensation product after the same has been substantially freedfrom uncombined phenols, and having a boiling point exceeding that ofWater.

3. An electrical insulating composition comprising an initial phenoliccondensation product capable of transformation by simple heating into aninfusible body, and a solvent therefor, containing neutral oil.

4. A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin, said product beingfree from uncombined formaldehyde and capable of transformation b simpleheating into an infusible body and an organic solvent therefor.

5. A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin and an organicsolvent therefor, said solvent being of the hydro-carbon type, andcharacterized by its high insulating value, its immiscibility withWater, and its capability of dissolving the said initial condensationproduct, after the same has been substantially freed from uncombinedphenols.

61A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin and an organicsolvent therefor, said solvent being of the hydro-carbon type, andcharacterized by its high insulating value, its immiscibility WithWater, and its capability-of dissolving the said initial condensationproduct, after the same has been substantiallyfreed from uncombinedphenols, and having a boiling point excecding'that of Water.

71A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin, transformable bysimple heating into an infusible body, and an organic solvent therefor.

8. A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin, transformable bysimple heating into an infusible body, and an organic solvent therefor,said solvent being of the hydro-carbon type, and characterized by itshigh insulating value, its immiscibility With Water, and its capabilityof dissolving the said initial condensation product, after the same hasbeen substantially freed from uncombined phenols.

9. A composition comprising an amorphous product resulting from thereaction of phenols and anhydro-formaldehyde-anilin, transformable bysimple heating into an infusible body, and an organic solvent there-'for, said solvent being of the hydro-carbon LEO H. BAEKELAND.

Witnesses: 7

AUGUST GoT'rHELr, MARY E. SCHOLDING.

